Margaret Howe lived with a dolphin for ten weeks in the 1960s
dailymail.co.uk
dailymail.co.uk
This article fails to mention a few important details that I'm sure the BBC documentary will. The lead researcher was very much into drug culture and Margaret said in the podcast that he gave drugs to some of the dolphins (not Peter) hoping that it would "open their mind" and help with the language development. I don't remember clearly, but I'm not sure if the podcast mentioned the timeline of the experiment. I was surprised to read it was only 10 weeks.
Everybody knows that dolphins can not be safely drugged. They stop to breath and die if you try to use sedatives or anesthesia.
http://www.theguardian.com/environment/2014/jun/08/the-dolph...
This same thing happened to one of the dolphins that played flipper on TV causing the dolphin's trainer to become an anti-captivity activist.